Seats with adjustable seat backs have been widely used in motor vehicles. The adjustability of the angular position of the seat back allows positioning that provides the best support or comfort. The seat back of an automobile seat is typically pivotably mounted relative to a seat base or seat bottom, and a recliner is used for adjusting the seat back position. The recliner typically employs some form of ratchet mechanism and is mounted on the side of the reclining seat. To adjust the position of the seat back, the ratchet mechanism is disengaged so that the seat back can be moved to a new position. The ratchet mechanism is then reengaged to hold the seat back in the new position.
The ratchet mechanism of the recliner typically has engagement teeth. The teeth can be made large to withstand sudden changes in the velocity of a motor vehicle. Using larger gear teeth, however, is associated with the disadvantage of reduced resolution of the position adjustment, and there is increasing demand for ever finer increments of seat back adjustment. Additionally, on certain cars, such as many two-door vehicles, the seat backs of the front seats can be further folded down or dumped to allow access to seats in a second row. Such designs naturally do not lock the seat back when the seat back is being dumped, and increasingly original equipment manufacturers are requiring that seat backs be lockable at all times.
Uni-directional inertial latches have been employed in the recliner to lock or latch the seat back, principally in seats where the seat back may be dumped to allow access to a second row of seating. The inertia latch is typically responsive to gravity as the seat back moves forward to move the latch to a non-engaging release position and is responsive to sudden deceleration created by a rapid reduction in speed to move into a locking position which prevents the seat back from moving forward. To provide even load distribution across the seat typically a second recliner is mounted on the other side of the seat back, connected by a slave wire.
Previous designs for recliners with uni-directional inertia latches are unsatisfactory in that the mechanisms are not responsive to sudden accelerations, and the strength of the seat back and seat base must be enhanced, driving up costs and complexity of the design. A safety locking device is disclosed in U.S. Pat. No. 3,848,923 to Dehler showing several versions of a mechanism for controlling the seat back in response to rapid changes in velocity in two directions. However, the locking devices shown in Dehler are complicated, costly, and require numerous separate components to achieve the desired bi-directionality of the locking device.
In view of the foregoing, it is an object of the present invention to provide an inertial latching device of a simple, elegant design for use on a reclining seat to securely lock the position of the seat back that is bi-directional, that is, the latch secures the seat back position during both rapid acceleration and rapid deceleration.
It is another object of the present invention to provide a bi-directional inertial latch of a simple, elegant design that does not compromise the resolution of seat back adjustment. To that end, it is an object of the present invention to provide a bi-directional inertia latch device for a recliner that may be mounted separately from the recliner.
It is a related object of the present invention to provide such a latching device of simple and elegant design that automatically operates to lock the position of the seat back during sudden changes in speed, and automatically releases the seat back after the sudden change has passed so that it does not interfere with the seat back position adjustment under normal conditions.
It is yet another related object of the present invention to provide such a latching device that is highly reliable in operation.
It is yet another related object of the present invention to provide such a bi-directional inertia latching device on a simple and elegant design which, when the seat back is in a reclined position, engages the seat back during rapid deceleration before the seat back is returned to a full upright position.